beautiful b physics at the tevatron iop hepp half day meeting results from the tevatron imperial...

Beautiful B Physics at the TevatronBeautiful B Physics at the TevatronBeautiful B Physics at the TevatronBeautiful B Physics at the Tevatron

IOP HEPP half day meeting

Results From the Tevatron

Imperial College London, 21 September 2005

Rick Jesik

Imperial College London

Representing the DØ and CDF collaborations

B Physics at Hadron CollidersB Physics at Hadron CollidersB Physics at Hadron CollidersB Physics at Hadron Colliders Pros

● Large production cross section – 300 Hz of reconstructable B’s

● All b species produced

B, B0, Bs, Bc, b, b

● We get to look for the Higgs at the same time

Cons

● Large combinatorics and messy events

● We only write about 50 Hz of data total, which we have to share with other physics

● Inelastic cross section is a factor of 103 larger with roughly the same pT spectrum – difficult to trigger on B’s

● Many decays of interest have BR’s of the order 10-6 – hard to separate from “regular” B decays at the trigger level

● Difficult to detect low pT photons and pi0’s from B decays

Tevatron LuminosityTevatron LuminosityTevatron LuminosityTevatron Luminosity Over 1 fb-1 of collisions have been delivered to the

experiments so far in Run II● Todays results based on ~ 0.5 fb-1

● UK institutions contribute to every analysis shown

The CDF Run II DetectorThe CDF Run II DetectorThe CDF Run II DetectorThe CDF Run II Detector

● New silicon vertex detector inner layer at 1.35 cm

● New central tracker Excellent mass

resolution

● Extended coverage

● TOF and dE/dx particle ID

● Second level impact parameter trigger Allows all hadronic B

decay triggers

The DØ Run II DetectorThe DØ Run II DetectorThe DØ Run II DetectorThe DØ Run II Detector

● Silicon vertex detector || < 3.0

● Central fiber tracker and pre-shower detectors || < 1.5

● 2 T solenoid magnet

● New low pT central muon trigger scintillators

● New forward system Excellent muon purity

and coverage: || < 2.0

● Second level silicon track trigger being commissioned, B tagging at 3rd level now

CDF Level 2 Silicon Vertex Trigger● Good IP resolution

● Trigger on displaced tracks

● beamspot reconstruction

update every ~ 30 seconds

● IP resolution: ~ 50 m

35 m beam size + 35 m

● Buffered vertex detector information allows for hadronic track trigger

d = impact parameter

Primary Vertex

Secondary Vertex

BLxy

CDF Silicon Vertex Trigger (SVT)CDF Silicon Vertex Trigger (SVT)CDF Silicon Vertex Trigger (SVT)CDF Silicon Vertex Trigger (SVT)

DDØ ExtendedØ Extended Tracking Coverage Tracking CoverageDDØ ExtendedØ Extended Tracking Coverage Tracking Coverage

Data from semileptonic decays (B D* X)

pT of soft pion from D*D0

η

of all B signal particles

Tracking extended out to || < 3.0 for vertex finding and tagging

B triggers at the TevatronB triggers at the TevatronB triggers at the TevatronB triggers at the Tevatron Dimuons – J/ modes

● pT > 1.5 - 3.0 GeV

● CDF central, DØ out to || < 2.0

Single muons – semileptonic decays, tagging triggers● DØ: very pure central track matched muons with pT > 4 GeV

require additional tracks at medium lums

require impact parameters, phi mass, at high lums

● CDF: pT > 4 GeV/c, 120 m < d0(Trk) < 1mm, pT(Trk) > 2 GeV/c

CDF two displaced vertex tracks - hadronic samples● pT(Trk) >2 GeV/c, 120 m < d0(Trk) < 1mm, pT > 5.5

GeV/c

DØ B Samples DØ B Samples DØ B Samples DØ B Samples Mode evts / 100pb-1

J/ + - 1.14 M

B+ J/ K+ 1700

Bd J/ K*0 740

Bd J/ K0S 40

Bs J/ 100

b J/ 25

Bc J/ X 65

X(3872) J/ + - 230

B D** v 210

B** B 150

Bs Ds1 X 4

B+ D0 + X 46.2 K

Bd D*- + X 10 K

Bs Ds() X 2900

Bs Ds(K*K) X 2500

485 pb-1

Ds1+ → D*+ KS

0

Ds → 13339 ± 277

460 pb-1

CDF B SignalsCDF B SignalsCDF B SignalsCDF B Signals

J/● 2.7M candidates in 360

pb-1

● ~15%: B decay

B0D-+

● 6k candidates in 360 pb-

1

● Two IP track trigger sample

Lifetime MeasurementsLifetime MeasurementsLifetime MeasurementsLifetime Measurements Hadron collider experiments are now making precision

measurements of Bs, b, Bc , B0, B- lifetimes

Tests of HQET, OPE, NLO QCD

Input to other measurements

Measure/predict ratios to minimize systematic uncertainties

LO 1.01(3) 1.00(1) 0.93(4)

NLO 1.06(3) 1.00(1) 0.90(5)

NLO+ 1.06(2) 1.00(1) 0.88(5)

)(

)(

d

s

B

B

)(

)(

d

b

B

)/1( 4

bmO

)(

)(

dB

B

Theory predictions

reduced disagreement with data

DØ Semileptonic BDØ Semileptonic BssDØ Semileptonic BDØ Semileptonic Bss

Bs→DsX

Large data sample from muon triggers ~400 pb-1

Resolutions and K factors from data semileptonic modes of B0,B-

Include charm backgrounds in the fit (wide tails) 057.0043.0420.1 sB

World Best Measurement !

CDF Hadronic modesCDF Hadronic modesCDF Hadronic modesCDF Hadronic modes First lifetime results to use events triggered by Silicon

Vertex Trigger

● Trigger IP cuts bias lifetime distributions but provides large all hadronic decay samples – no K factors needed

● Correct for trigger bias using Monte Carlo – verified with B+

● Systematic uncertainties ~ 4-5 m

CDF Lifetimes in Hadronic ModeCDF Lifetimes in Hadronic ModeCDF Lifetimes in Hadronic ModeCDF Lifetimes in Hadronic Mode

(B+) = 1.661±0.027±0.013 ps (B0) = 1.511±0.023±0.013 ps(Bs) = 1.598±0.097±0.017 ps

DØDØbb lifetime lifetimeDØDØbb lifetime lifetime

2D mass – decay length fits: 61 ± 12 signal events

(b) /(B0) = 0.87 ± 0.17 ± 0.03

ΛJΛb /

Consistent with new theory

CDF BCDF Bcc mass massCDF BCDF Bcc mass mass

“Evidence” of Hadronic BcJ/ ● Significance: 3.5

● M(Bc) = 6287.0±4.8±1.1 MeV

Good agreement with recent Lattice prediction of 6304±12+18 MeV –FHPQCD, Fermilab Lattice, UKQCD–PRL 94 2005

DØ BDØ Bcc mass and lifetime mass and lifetimeDØ BDØ Bcc mass and lifetime mass and lifetime

N(Bc) = 95 ± 12 ± 11

M(Bc) = 5.95 ± 0.14± 0.34 GeV/c2

(Bc) = 0.45 ± 0.12± 0.12 ps

.

Theory vs. DataTheory vs. DataTheory vs. DataTheory vs. Data

Measured

1.076(8) 0.92(3) 0.81(5)0.45(12)

ps

Theory 1.06(2) 1.00(1) 0.88(5) 0.36(?) ps

)(

)(

d

s

B

B

)(

)(

d

b

B

)(

)(

dB

B

2005 HFAG world average lifetimes vs. theoretical predictions

)( cB

Precision on Bs and Lb measurements will continue to increase – may show discrepancy with theory. Bc prediction needs to be revisited.

The BThe Bs s SystemSystemThe BThe Bs s SystemSystem

M12 stems from the real part of the box diagram, dominated by top

G12 stems from the imaginary part, dominated by charm

Heavy and light Bs eigenstates are expected to have different widths

tB

tBiM

tB

tB

dt

di

s

s

s

s

2

1, 22

qpevencpBqBpB

oddcpBqBpB

ssH

ssL

ssfrom Bfrom Bss→J/→J/ ssfrom Bfrom Bss→J/→J/ Relation of matrix elements to decay and oscillation parameters:

In the Standard Model:

● The CP violating phase, is expected to be small

● Mass eigenstates are ~ CP eigenstates with definite lifetimes

The J/final state is a mixture of CP states

● L=0, 2; CP even; (AA)

● L=1; CP odd; (A┴)

Assuming no CP violation in the Bs system, measure two Bs lifetimes, L and H, (or / and ) by simultaneously fitting time evolution and angular distribution in untagged Bs J/ decays

CDF result last summer: 01.065.0/ 25.0

33.0

cos2

2

12

12

HL

LH MMMm

12

12argM

Transversity Analysis Transversity Analysis Transversity Analysis Transversity Analysis z

x

y

J/ Rest Frame

K+

K-

+

-

x

y

Rest Frame

J/

K+

K-

=transversity

DØDØssfrom Bfrom Bss→J/→J/DØDØssfrom Bfrom Bss→J/→J/ CDF result fit to ,

angles giving AA, A ┴, phase,

R ┴ =|A

┴(0)|2

New DØ result integrates over the angles using MC efficiency

Fit technique similar to lifetime fit, but adds angle dependence

Provides values for , , and R ┴

- no amplitudes or phase

2222

||

2

0 sin4

3)(cos1

8

3)()(

costAtAtA

d

td

483±32

D0 Preliminary

DØDØss Results ResultsDØDØss Results Results Fit Results:

02.010.017.0

20.021.0

08.039.1)(

27.040.0

13.014.0

0

R

psBs

DØ PreliminaryD0 Preliminary

D0 Preliminary

Additional ConstraintsAdditional ConstraintsAdditional ConstraintsAdditional Constraints

Include fs constraint from

semleptonic measurements:

16.017.0

2

2

23.0

05.043.1

21

21

psfs

fs

D0 Preliminary

((//))ss Combined Results Combined Results ((//))ss Combined Results Combined Results

((//))ss Future Future ((//))ss Future Future

DØ fs & /

D projection, CDF has similar sensitivity

Both experiments plan tagged CPV analysis

BBss mixing mixingBBss mixing mixing

Measures least known side of unitary triangle

Can not be done at B factories Difficult measurement – requires:

● High yield, good S/B● Oscillations are rapid, so we

need excellent lifetime resolution

● Flavor tagging

DDØØ Bs Mixing Bs MixingDDØØ Bs Mixing Bs Mixing Use Semileptonic Decay mode:

BsDs, Ds

Flavor taggingFlavor taggingFlavor taggingFlavor tagging

Opposite side lepton

Q of the highest pT muon or electron in the event separated in from the signal B by 2.2 rads.

Opposite jet charge

iT

iiT

Σp

.qΣpQJet

Require |Q| > 0.2

b

b d

du

0

B

b

b d

du

0B

u u

Same side track charge

Q of the highest pT (or lowest pTrel) track in a cone (dR < 0.7) around the B

DDØØ Flavor Tagging Variable Flavor Tagging VariableDDØØ Flavor Tagging Variable Flavor Tagging Variable

Measure Tagging using BMeasure Tagging using Bdd and B and B++Measure Tagging using BMeasure Tagging using Bdd and B and B++

Measured AssymetryMeasured AssymetryMeasured AssymetryMeasured Assymetry Fit flavor tagged signal in bins of proper decay

length

Corrected AsymmetryCorrected AsymmetryCorrected AsymmetryCorrected Asymmetry

Measured asymmetry must be corrected for● Decay length resolution (tuned MC to look like data)

● Reconstruction efficiency vs. decay length

● Sample composition

Sample Composition and K factorsSample Composition and K factorsSample Composition and K factorsSample Composition and K factors

Decay Sample compositio

n

Bs→Dsμν 20.6%

Bs→D*sμν 57.2%

Bs→D*0sμν 1.4%

Bs→D*1sμν 2.9%

Bs→DsDsX 11.3%

B0→DsDX 3.2%

B-→DsDX 3.4%

Bs mixing limit – Amplitude fit methodBs mixing limit – Amplitude fit methodBs mixing limit – Amplitude fit methodBs mixing limit – Amplitude fit method

Bs mixing LimitBs mixing LimitBs mixing LimitBs mixing Limit

Adding K*K Decay ModeAdding K*K Decay ModeAdding K*K Decay ModeAdding K*K Decay Mode

DDØØ combined Bs mixing limit combined Bs mixing limitDDØØ combined Bs mixing limit combined Bs mixing limit

DØ Prelim

(610 pb-1)

CDF Bs Signal ReconstructionCDF Bs Signal ReconstructionCDF Bs Signal ReconstructionCDF Bs Signal Reconstruction

526±33 events

Hadronic channel Semileptonic channel

CDF Flavor Tagging CDF Flavor Tagging CDF Flavor Tagging CDF Flavor Tagging

Tag type D2 (%)

Muon (0.70±0.04)%

Electron (0.37±0.03)%

2ndary vtx (0.36±0.02)%

Displaced track

(0.36±0.03)%

Highest p jet

(0.15±0.01)%

Total ~1.6%

Muon Tag

CDF BCDF B00dd Mixing (Semileptonic) Mixing (Semileptonic)CDF BCDF B00dd Mixing (Semileptonic) Mixing (Semileptonic)

)( KDXlDB

Muon Tag

)( 00 KDXlDB

Muon Tag

Validation of the flavor tag using B0 and B+ sample

● md = 0.498±0.028±0.015) ps-1

CDF BCDF Bss Mixing Result Mixing ResultCDF BCDF Bss Mixing Result Mixing Result

Semileptonic Channel● Sensitivity = 7.4 ps-1

● Limit: 7.7 ps-1

Semileptonic + Hadronic● Sensitivity: 7.4 8.4 ps-1

● Limit: 7.7 7.9 ps-1

Tevatron+World Combined ResultTevatron+World Combined ResultTevatron+World Combined ResultTevatron+World Combined Result World Average + TeV

Run II● Sensitivity: 18.8 ps-1

● Limit 14.4 ps-1

World Average● LEP, SLD, CDF run I

● Sensitivity: 18.2 ps-1

● Limit: 14.5 ps-1

Bs Mixing SensitivitiesBs Mixing SensitivitiesBs Mixing SensitivitiesBs Mixing Sensitivities

Not too bad for our first try, but we can do much better….

Near term DNear term DØØ B Bss Mixing Reach Mixing ReachNear term DNear term DØØ B Bss Mixing Reach Mixing Reach

Semileptonic reach ~14 ps-1 in 1 fb-1

CDF Near Term CDF Near Term mmss Reach ImprovementsReach ImprovementsCDF Near Term CDF Near Term mmss Reach ImprovementsReach Improvements

Add new tagging algorithms

● same side Kaon

Add more channels

● K*K, 3

Add signals from other triggers

● 4GeV-lepton + 1 displaced track trigger adds 3x data

Improve decay time resolution with event by event primary vertex reconstruction

2 displaced track trigger

expect combined hadronic and semileptonic sensitivity ~ 15ps-1 in 1 fb-1

Inte

gra

ted

Lu

min

osi

ty (

fb-1)

www.fnal.gov/directorate/DOE_TeVOps05_Review.html

DDØ Upgrades for High LuminosityØ Upgrades for High LuminosityDDØ Upgrades for High LuminosityØ Upgrades for High Luminosity

Trigger Bandwidth Upgrade ● current limit for B-Physics

triggers is rate to tape

● Proposal to add 50 Hz of dedicated B physics bandwidth

Silicon Layer-0 ● add new, rad hard Layer-0

at R = 1.7 cm inside present detector around beam pipe

● Impact Parameter resolution: 55→35 m at 1 GeV

● Installed this spring

DDØØ BBss Mixing Mixing with with Hadronic ModesHadronic Modes DDØØ BBss Mixing Mixing with with Hadronic ModesHadronic Modes

Difficult trigger, small BR’s● trigger on single muon from other B in event

● ~ 10x less events, but we are starting to see hadronic signals

● single muon triggers saturate extra rate to tape at low lums

● specialized Bs triggers now running unprescaled at all lums

● DAQ upgrade proposed to write even more inclusive muon data to tape

Excellent tagging powerε D2 ~ 40 - 70 %, self tagging trigger!

Excellent proper time resolution with new silicon layer● ~ 50 - 75 fs

CDF has added similar trigger for high lums

Long Term BLong Term Bss Mixing Reach Mixing ReachLong Term BLong Term Bss Mixing Reach Mixing Reach

Combined Tevatron can Fully cover SM range by the end of Run II

B factories and Tevatron will continue to shrink the SM allowed region

CP violation at the TevatronCP violation at the Tevatron CP violation at the TevatronCP violation at the Tevatron

~900 evts/180 pb-1 in initial CDF data, taken with still non optimized detector/trigger.

Now much better: ~2700 / 360 pb-1

What we measure:

ConclusionsConclusionsConclusionsConclusions The Tevatron continues to perform very well, and is a great place to

do B physics● 1fb-1 of data has been delivered, on track for 4-8 fb-1 of data by 2009

Both CDF and DØ have made significant B lifetime measurements

● B+, B0 are competitive, b , Bs are the best in the world

● ()s measured and is not exactly at SM value (but is within errors)

More data will confirm SM or point to new physics

Both Experiments are poised to attack Bs mixing

● First ms limits and sensitivity have been presented

● Look for significant contributions to the world knowledge by next summer

● We have an excellent chance to either measure Bs mixing, or exclude its SM model predicted values by the end of Run II

The Tevatron has a rich B physics program beyond what I’ve shown here; including production properties, searches for new physics in rare decays, CP violation, and other CKM measurements…